NEW YORK (Reuters Health) - A new study adds to evidence that infants and toddlers are not too young to develop nasal allergies, particularly if their parents have a history of the bothersome condition.

In a study of more than 1,800 18-month-old children, French researchers found that 9 percent had suffered symptoms suggestive of nasal allergies, also called allergic rhinitis, in the past year. Those toddlers were also more likely than the rest of the study group to show certain objective markers of allergies.

While it is known that infants do suffer certain allergies, like food allergies, there have been questions about whether allergic reactions to airborne irritants like dust mites, pet dander and mold begin as early as the first year of life.

The uncertainty arises in large part from the fact that it is hard to tell whether babies' runny, stuffy noses signal a cold or other respiratory infection, or a possible allergy.

"It's hard to know what's happening with very young children when you are dealing with them on a one-on-one basis," said Dr. Henry Milgrom, a professor of pediatrics at National Jewish Health in Denver.

Babies and toddlers frequently come down with colds, so in most cases parents should not assume that recurrent runny noses signal an allergy, according to Milgrom, who was not involved in the new study.

"I think a lot of new parents are unprepared for how many colds babies and toddlers get," Milgrom noted. Parents, he said, should be aware that frequent nasal symptoms are to be expected, particularly if a baby or toddler is around other young children.

But by including objective tests of allergy indicators, the new study helps confirm that some babies and toddlers may in fact suffer from nasal allergies, according to Milgrom.

The situation parallels that of asthma: Many babies and young children have occasional episodes of wheezing, usually related to a viral infection, and most are not later diagnosed with asthma. But some are.

For the current study, published in the journal Allergy, researchers led by Dr. Isabelle Momas of Paris Descartes University surveyed parents of 1,850 children 18 months old. They also took blood samples from the toddlers to test for biological indicators of a nasal allergy.

Overall, 9 percent of the children had suffered possible nasal allergy symptoms in the past year -- meaning their parents said the children had had trouble with sneezing or a stuffed, runny nose even in the absence of a cold or the flu.

These toddlers were also more likely than those without such symptoms to show certain biological markers of an allergy. Nineteen percent had an elevated concentration of inflammatory immune-system cells called eosinophils; that compared with 12 percent of children whose parents reported no allergy-like symptoms.

In addition, 5.5 percent of toddlers in the former group were found to have immune system antibodies to an inhaled allergen -- in most cases, to house dust mites or cat dander. That compared with just under 3 percent of the other children.

"These results support the hypothesis that allergic rhinitis could begin as early as 18 months of life," Momas and her colleagues write.

They add that the possibility of a nasal allergy should be considered in babies and toddlers with persistent symptoms, particularly if the parents have had such allergies.

Among the children with allergy-like symptoms in this study, 44 percent had at least one parent with a history of nasal allergies, versus 35 percent of the other children. When the researchers accounted for a number of other factors -- like parents' income and smoking habits -- they found that having two parents with a history of nasal allergies doubled the odds of a toddler having allergy-like symptoms.

Milgrom agreed that a parental history of nasal allergies should raise the level of suspicion that a young child's symptoms might be related to allergies rather than recurrent colds. He said the same is true when the child has a history of eczema -- inflammation of the skin that, in infancy, is typically triggered by a food allergen.

If nasal allergies are suspected, Milgrom said, the treatment options include antihistamines, inhaled corticosteroids and a medication called cromolyn, all of which can be used in babies as young as 6 months under a doctor's direction.

But there are non-drug options as well. Salt-water nasal washes can help clear mucus and inhaled allergens from the nose, and they may be tried more often with young children than with adults, Milgrom noted.

Curbing babies' and toddlers' exposure to the suspected allergen should also help. House dust mites were the most common apparent allergy trigger in this study, and tactics such as covering kids' mattresses and box springs with dust-proof covers can be effective.

As it stands, diagnosis of nasal allergies in very young children is generally based on symptoms and whether there is a family history of allergies or a history of eczema in the child. Milgrom said he normally would not do blood tests in children so young.

Whether the current study might encourage some doctors to do such testing more often remains to be seen, according to Milgrom. But he also said he would not expect one study to alter clinical practice.